The invention relates to a code converter for processing switching information signals, which comprises a protection circuit for limiting a current flowing in a telephone exchange wire.
The invention likewise relates to a protection circuit for a code converter.
A code converter is necessary to couple analogue switching exchanges to a PCM (Pulse Code Modulation) transmission link. The code converter converts analog switching codes (DC signals) into digital codes and is also used for converting digital codes into analog switching codes.
A code converter of this type is known from Siemens Zeitschrift 49, volume 7, pages 466-472. The telephone exchange wires i.e. the speaking wires a and b as well as the seizure wire c are connected to protection circuits (not further defined) of the code converter to protect the electronic circuits of the code converter against overvoltages and overload (see page 469). An overload or an intolerably high current level occur, for example, in the case of unintentional direct contact of the telephone exchange wires with the lines of the exchange power supply.
It is an object of the invention to provide a code converter of the type defined in the opening paragraph, which is protected against overload by a protection circuit.